Multiple telegraphy



(No Model.)

0. SELDEN.

MULTIPLE TELEGRAPHY.

No. 378,181. Patented Feb. 21, 1888 QwMZ/aooao M M Qwvewtoz UNITED STATES PATENT OFFICE.

CHARLES SELDEN, OF BALTIMORE, MARYLAND.

MULTIPLE TELEGRAPHY.

SPECIFICATION forming part of Letters Patent No. 378,181 dated February 21, 1888.

Application filed April 15,1887. Serial No. 234,967. (No model.)

To aZZ whom it may concern:

Be it known that I, CHARLES SELDEN, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Multiple Telegraphy, of which the following is a specification.

My invention relates to multiplex telegraphy,

' and has for its object to improve the construction and arrangement of telegraphic systems, whereby they are adapted for the simultaneous use of any of the ordinary systems of telegraph y and induced-current systems of telegraphy or telephony on the same linewire.

Heretof ore attempts have been made to make use of the same line-wire for the simultaneous transmission of various kinds of currents, and it has been ascertained that the induced-current signals may be superposed upon a linewire over which Morse signals are being sent by connecting the said inducedcurrent-signal apparatus to the main line by means of separators or inductors in the form of condensers or inductoriums,which allow the high-tension currents of the induced-current signals to pass, but which are opaque to the passage of the lower-tension Morse or other telegraphic signals. Even when this kind of aseparator has been used it has been found that the making and breaking of the circuit in producing the Morse signals would cause such an abrupt charge and discharge of the line that the effects thereof would be distinguished in the receiving apparatus of the induced-current apparatus, and the reception of signals therein would be more or less interfered with. This objection has been overcome by rendering gradual the emission and extinction of the Morse-signal currents, so that the line would become charged and discharged gradually, thereby lessening the disturbances in the induced-current-signal apparatus. Various means have been suggested for rendering gradual these telegraphic signals, one of the means consisting in placing in the main telegraphic line magnet coils or helices with or without magnet-cores. Vhile such magnets have been found effectual in graduating the currents,they areimpracticable for various reasons, and principally for the reason that a large amount of resistance is thereby interpolated in the line, requiring more battery-power to transmit signals over a given length of line, and by the increase of battery-power necessary to be employed the currents were not graduated sufficiently, and, furthermore, the magnetic effects from the cores increased the difficulties experienced in multiplex-telegraph working by thus limiting their use to comparatively short circuits or lines.

In my prior patent, No. 358,890, I have described and shown several improvements rclating to the use of graduators, in which a portion of the telegraphic circuit is arranged in multiple arc and the graduators are interpolated in the arc circuits, and by this arrangement the telegraphcurrents will divide thenr selves in accordance with well-known laws, depending upon the amount of resistance in each circuit.

I have also shown in said patent a manner of connecting the induced-current system to the are circuits, instead of in the main line, as well as a manner of interpolating two sets of graduators in each are circuit and connecting the induced-current system between the graduators.

My present invention relates to an improvement on said system; and it consists in certain ways, more particularly pointed out herein after, of connecting the induced-current system to the main lineboth at terminal and way stations, and more especially an arrangement whereby the disturbances commonly called tailings, or those due to the magnetic induction discharges, are overcome,and,further, in certain arrangements of the circuits whereby different messagcs may be sentand received without interference with each other.

Referring to the accompanying drawings, Figure 1 is a diagrammatic arrangement of a line, showing terminal and way stations involving my invention. Fig. 2 is a similar diagram showing a way-station with a different arrangement of circuits also embodying my invention.

In the various figures, A represents a main line of any ordinary or multiplex telegraph system; B, the main battery; 0, the key, and I) the receiving-instrument of such system. At some convenient point in the line, as at E, the main line A is divided into a multiple-are circuit, shown in this instance as consisting of three divisions, though any convenient number may be used, and in each of these are circuits is interpolated one or more cmrent-grad uators, G, of anysuitable or desirable construction.

It will be seen that the current on the main line from the battery at either end will divide at the point E or E, where the arc circuits begin, and the amount of the current traversing each of the arc circuits will be directly proportional to the resistance that each one bears to the sum of all, and if the resistance of the three are circuits shown is equal it will be understood that one-third of the battery-powm i will traverse each are and the graduator or graduators therein and meetagain at the junction of said circuits with the main line. current will pass thereon with slightly'diminished potential, while at the same time it will be effectually graduated.

Attached to the main line beyond the j unetion of the are circuits are branch lines If, in eluding induccdeurrent transmitting and receivingdeviccs T and It, and these circuits are connected to the main line by means of a separator, I, of any convenient and well-known form, indicated in the drawings as condensers.

It will be understood that these separators will not interfere with induced-current sig nals and are practically opaque to the ordinary telegraph-signals, and especially when such signals are graduated, and the graduators are practically opaque to the induced current signals. I have found that the graduators sometimes cause what is known as tailings in the transmission of signals, and especially is this the case when the graduators consist of a coil and core, and these tailings or disturbances interfere with the rapid transmission of signals, causing the spaces between the signals to be obliterated to a greater or less extent and the signals to run into each other or bejoined together. In ordertoovcrcome this disturbance, I attach to the main line a branch circuit, J, and include therein a condenser, K, and I have found the discharge from this condenser will neutralize the tendency of the graduators to cause tailings and will render the signals sharp and clear. This condenser branch may be connected to the main line at different positions, as shown, the connection at the left hand of the drawings being with the line itself and the connection at the right hand being with one of the branches of the multiple-arc portion of the line, or a separate condenser branch may be connected with each of the multiple are branches of the line.

In Fig. 1, at the point X, I have shown one arrangement of circuits at a way-station between the two terminal stations, and while it is not absolutely necessary to graduate the currents at a way-station, as the messages would he graduated at the terminals, I have found it convenient in manyinstanees tograduate the currents at this point, and by so doing I am enabled to transmit messages in different directions without interference with each The J l other. Thus, for instance, the derived line L at the waystation can communicate with the terminal stationY and the derived line M can communicate with the terminal station Z simultaneously without interference with each other, and the graduating devices G, arranged between these derived lines, will prevent the l induced current from either one of the lines l passing through to the opposite terminal sta- 1 tion and without interfering in any respect with the ordinary telegraph-currents on the main line between the terminal stations.

Vthile I have shown both of the derived lines L )I as emanating from the same are circuit, it is obvious and sometimes preferable that they should emanate from different 1 branches of the are circuit, as shown in dotted lines at a.

In order that the branch lines L and M can communicate with each other direct, I place a shunt, N, around the graduators G at the waystation and include therein a condenser, U

l l l current signals from the derived line L to the line M. This arrangement may also be used to permit the passage of the induced-current signals from one terminal station to the other, as from Y to Z, as by this arrangement the graduating devices are cut out of the circuit and the imluccd-current signals allowed to pass without obstruction. Another way of accomplishing this result is shown in Fig. 2, in which the condenser-shunt Iis connected with the mainline beyond the point of junction of the multiple-arc circuit on either side. This condensershunt also accomplishes another result in that it allows the derived line L, forinstance, to communicate with either of the stations Y Z, for the reasons before stated.

In order that the invention may be more clearly understood, suppose the stations Y and Z to represent \Vashington and New York, for instance, and the station X to be a waystation, as Baltimore or Philadelphia. It will be seen that the Morse or other ordinary telegraplrsignalswill he graduated atthe terminal stations, and if the induced-current system is to be used between the terminal stations only, or it is only desired to render the ordinary current-signals inaudible in all of the inducedcurrent signals, the graduators at the waystation may be omitted and the derived lines connected directly with the main line; but if it is desired that the way-station may communicate independently with either of the terminal stations without the other terminal Sta tion being aware of the fact, I place the graduators in the main line at the way-station, as represented in Fig. 1, and connect the derived lines to either one or several of the mutipleare branches; and it will be seen from the above explanation that the way-station may communicate directly with the terminal Y through the derived lines If and L and with the terminal Z by means of the derived lines M and II, and the graduators at the way-station will prevent anyinterferenee between the and this permits the passage of the induced IOC messages being sotransmitted. In all of these instances the condenser-shunt J will overcome l the effects of the'tailings or discharge of the graduators or otherinstruments in the line.

From the above it will appear that I am enabled to utilize a single line for the simultaneous transnrission of ordinary-current signals and induced-current signals, and that these induced-current signals may be used from terminal to terminal of the line, or may be used as way-lines, at pleasure, and in all cases without interfering with each other or with the ordinary-current signals.

In the diagram, Fig. 1, I have shown different arrangements of graduating devices and circuit-connections at each station for the sake of illustration; but it will be understood that I may use any one of the arrangements at all the stations on a line, or any two of them at the terminal stations, and any one at the waystations without deviating from my invention.

Having thus described my invention, what I claim, and desire to secure by Letters Patent,

1. The combination, with a telegraph-line composed in part of branch or multiple-arc circuits and graduators arranged in said branch circuits, of a derived line connected to said main line by separators, and a condenser branch connecting the line to ground, substantially as described.

2. The combinaiion,wilh a telegraplrlinc a part of which is composed of multiplearc circuits, of graduators in said are circuits, derived circuits connected with said are circuits, and condenser-shunts connecting said multiple-arc circuits to earth, substantially as described.

3. The combinatiou,with a telegraph-line a part of which, at a way-station, is composed of branch or multiple-arc circuits, of graduators in said branch circuits, and a shunt, including acondenser, around the graduators in one of the arc circuits, substantially as described.

4. The combination, with a telegraph-line composed in part of multiple-arc circuits, of graduators in said multiple-arc circuits, derived circuits connecting said are circuits to ground, and a condenser-shunt around said 9 multiple arc circuits, substantially as described.

In testimony whereof I have signed my name to this specification in the presence oftwo subscribing witnesses.

CHARLES SELDEN.

\Vitnesses:

W. CLARENCE DUVALL, F. L. FREEMAN. 

